Answer:
They use those descriptions to make that piece of writing have more depth to it. Using those noises and whatnot paint a more vivid picture for those who read it. It can allow the reader to feel more connected with the story, seeing as they have more detail for what the actual characters are going though. They understand more of what the characters are seeing, feeling, hearing, etc. It gives the tone have more value and worth.
I don't have specific details from the story, but this is a start.
Hope I could help! ;)
